(j3.2006) Is really necessary?

Bill Long longb
Mon May 9 08:13:04 EDT 2016

On May 6, 2016, at 7:10 PM, Van Snyder <Van.Snyder at jpl.nasa.gov> wrote:

> A colleague tried to write a simple routine that would compute the size
> in bytes of an array (to track memory usage), deallocate it, test the
> status, and print a message if failure occurred.  Rather than writing

Rather than trying to do something obtuse why not just use Fortran:

mysize = storage_size(x)*size(x)
deallocate(x, stat=is)
if (is == 0) then
    used_space = used_space - mysize
    print *, ?failure to deallocate array"
end if


> one for every type and kind, he tried to make the dummy argument
> unlimited polymorphic.
> This fell afoul of
>        The actual argument shall be polymorphic if and only if the
>        associated dummy argument is polymorphic, and either both the
>        actual and dummy arguments shall be unlimited polymorphic, or
>        the declared type of the actual argument shall be the same as
>        the declared type of the dummy argument.
> Is this paragraph really necessary?  It seems that the object-oriented
> system ought to work just fine without it, albeit with some more words
> to describe how a dummy argument can be allocated if the actual
> argument's declared type is compatible with but not necessarily
> identical to the dummy argument's declared type.  The result would of
> necessity be that the dynamic type of the allocated entity is type
> compatible with the declared type of the actual argument if the actual
> argument is polymorphic, and the same type if it's not.  If there is no
> type spec in the allocate statement, the allocated type is the declared
> type of the actual argument.    Everything else, including deallocation,
> ought to work without additional explanation.
> Processors might endure some complication in creating descriptors to
> connect polymorphic dummy arguments to nonpolymorphic actual arguments,
> or actual arguments whose declared types are type compatible rather than
> identical.  The "type" member of the CFI_cdesc_t struct ought to serve
> for this purpose.  Because having a polymorphic dummy argument requires
> an explicit interface, a processor would know where this is required.
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Bill Long                                                                       longb at cray.com
Fortran Technical Support  &                                  voice:  651-605-9024
Bioinformatics Software Development                     fax:  651-605-9142
Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101

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